Setbacks are no fun. In fact, being told you’re not good enough -- for anything -- is about as enjoyable as having a tooth pulled minus the novocaine.

An unexpected setback can be a direct hit to your self-confidence. If things have gone well for a number of days, months or years and then all of a sudden -- bam! -- you receive negative customer feedback or a media release that paints your company in a less-than-stellar light, rebounding back to where you were can take some concerted effort.

As pervasive as successes and setbacks are in the startup world, they never become any easier to endure. If success has been a habit, setbacks can feel like shell shock. Similarly, if success has been fleeting then the tendency for complacency can easily settle in.

If a recent setback has set you, well, back, try these four mental exercises and rebuild your self-confidence:

1. Envision success.

The power of visualizing success is significantly undervalued. There’s a reason that Olympic, college and professional athletes have mental performance coaches who preach the power of visualization. By envisioning what your ideal “win” looks, smells and feels like, you create neural pathways for something that technically hasn’t happened yet but fool the brain into believing it has.

In other words, you navigate the same neural processes and secrete the same neural juices (that’s my phrase ) to execute a behavior as you did when you envisioned it.

If you don’t believe me, check this out: In one 12-week study, 30 people were assigned the task of increasing their pinky finger muscle. One group was given exercises to strengthen their pinkies while the other was told to envision their pinky fingers becoming stronger.

The results? The group that visualized improvement increased their pinky strength by 35 percent; the other group made zero improvements. The mind is a powerful thing.

2. Affirm and reaffirm yourself.

Stuart Smiley was on to something on Saturday Night Live (did I just reveal my age?) with his consistently cheesy self-affirmations. Affirmations bolster self-confidence by thinking of nothing but the good, and in doing so, act as a buffer for the challenge of the moment. The key to success with affirmations is to turn the momentary “I can do it” self-encouragement into a habit of positive self-talk.

3. Start a snowball of success.

Creating small wins throughout the day lets us experience the sensation of winning, which creates the biofeedback we need to crave it even more.

When you win at something -- no matter how big or small -- your body releases higher levels of testosterone and dopamine that create the "addiction" for more success. Greater testosterone levels increase your desire for more while also boosting your risk-tolerance. Dopamine helps you feel good about doing so (dopamine is the "feel good" neurochemical that tells the brain, "Hey, I like this!").

The more this cycle of small-wins biofeedback repeats, the larger the snowball grows.

4. Change your body language.

Social psychologist Amy Cuddy ruffled some feathers (in a positive way) with her groundbreaking research on how body position impacts self-confidence. In her famous TED talk, Cuddy reveals how we can change not only how we feel about ourselves but also how others perceive us simply by changing our body language. By engaging in power poses, or body positions that assume confidence, you subsequently begin to think and feel more confidently.

The good thing about self-confidence is that it never really goes anywhere. That is, the self-confidence that propelled you toward winning on your high school sports or academic team or elsewhere may require some personal digging to excavate it back to the surface, but that self-confidence never really leaves you. All you need are the right tools to dig.

Jeff Boss

Jeff Boss is a leadership coach with a focus on adaptability who leverages his previous careers as a Navy SEAL and business consultant to help clients accelerate success. Read more at www.adaptabilitycoach.com.